81901778 has 8 divisors (see below), whose sum is σ = 140403072. Its totient is φ = 35100756.

The previous prime is 81901753. The next prime is 81901793. The reversal of 81901778 is 87710918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×81901778² = 13415802479122568, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2925050 + ... + 2925077.

It is an arithmetic number, because the mean of its divisors is an integer number (17550384).

Almost surely, 2^81901778 is an apocalyptic number.

81901778 is a deficient number, since it is larger than the sum of its proper divisors (58501294).

81901778 is a wasteful number, since it uses less digits than its factorization.

81901778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5850136.

The product of its (nonzero) digits is 28224, while the sum is 41.

The square root of 81901778 is about 9049.9601104093. The cubic root of 81901778 is about 434.2746143676.

The spelling of 81901778 in words is "eighty-one million, nine hundred one thousand, seven hundred seventy-eight".